ORCID Profile
0000-0001-7703-7440
Current Organisations
Deakin University Burwood Campus
,
Griffith University
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Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.JBIOMECH.2018.11.036
Abstract: Soldiers regularly transport loads weighing >20 kg at slow speeds for long durations. These tasks elicit high energetic costs through increased positive work generated by knee and ankle muscles, which may increase risk of muscular fatigue and decrease combat readiness. This study aimed to determine how modifying where load is borne changes lower-limb joint mechanical work production, and if load magnitude and/or walking speed also affect work production. Twenty Australian soldiers participated, donning a total of 12 body armor variations: six different body armor systems (one standard-issue, two commercially available [cARM1-2], and three prototypes [pARM1-3]), each worn with two different load magnitudes (15 and 30 kg). For each armor variation, participants completed treadmill walking at two speeds (1.51 and 1.83 m/s). Three-dimensional motion capture and force plate data were acquired and used to estimate joint angles and moments from inverse kinematics and dynamics, respectively. Subsequently, hip, knee, and ankle joint work and power were computed and compared between armor types and walking speeds. Positive joint work over the stance phase significantly increased with walking speed and carried load, accompanied by 2.3-2.6% shifts in total positive work production from the ankle to the hip (p < 0.05). Compared to using cARM1 with 15 kg carried load, carrying 30 kg resulted in significantly greater hip contribution to total lower-limb positive work, while knee and ankle work decreased. Substantial increases in hip joint contributions to total lower-limb positive work that occur with increases in walking speed and load magnitude highlight the importance of hip musculature to load carriage walking.
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.GAITPOST.2017.04.002
Abstract: Body armor covers anatomical landmarks that would otherwise be used to track trunk and pelvis movement in motion analysis. This study developed and evaluated a new marker set, and compared it to placing markers on the skin and over-top of body armor. In our method, pelvis and trunk motions were measured using a custom-built sacral and upper-back marker cluster, respectively. Joint angles and ranges of motion were determined while participants walked without and with body armor. Angles were obtained from the new marker set and compared against conventional marker sets placed on the skin or over-top the body armor. Bland-Altman analyses compared the agreement of kinematic parameters between marker sets, while joint angle waveforms were compared using inter-protocol coefficient of multiple correlations (CMCs). The intra- and inter-session similarities of joint angle waveforms from each marker set were also assessed using CMCs. There was a strong agreement between joint angles from the new marker set and markers placed directly on the skin at key anatomical landmarks. The agreement worsened with markers placed on top of body armor. Inter-protocol CMCs comparing markers on body armor to the new marker set were poor compared to CMCs between skin-mounted markers and the new marker set. Intra- and inter-session repeatability were higher for the new marker set compared to placing markers over-top of body armor. The new marker set provides a viable alternative for researchers to reliably measure trunk and pelvis motion when equipment, such as body armor, obscures marker placement.
Publisher: Oxford University Press (OUP)
Date: 20-03-2021
Abstract: The purpose of this study was to investigate sex-specific lower limb biomechanical adaptations during a standardized load carriage task in response to a targeted physical training program. Twenty-five healthy civilians (males [n = 13] and females [n = 12]) completed a load carriage task (5 km at 5.5 km·h−1, wearing a 23 kg vest) before and after a 10-week lower-body–focused training program. Kinematics and ground reaction force data were collected during the task and were used to estimate lower limb joint kinematics and kinetics (i.e., moments and powers). Direct statistical comparisons were not conducted due to different data collection protocols between sexes. A two-way repeated measures ANOVA tested for significant interactions between, and main effects of training and distance marched for male and female data, respectively. Primary kinematic and kinetic changes were observed at the knee and ankle joints for males and at the hip and knee joints for females. Knee joint moments increased for both sexes over the 5 km distance marched (P & .05), with males demonstrating significant reductions in peak knee joint extension after training. Hip adduction, internal rotation, and knee internal rotation angles significantly increased after the 5 km load carriage task for females but not males. Differences in adaptive gait strategies between sexes indicate that physical training needs to be tailored to sex-specific requirements to meet standardized load carriage task demands. The findings highlighted previously unfound sex-specific responses that could inform military training and facilitate the integration of female soldiers into physically demanding military roles.
Publisher: Informa UK Limited
Date: 03-11-2015
DOI: 10.1080/00140139.2015.1092589
Abstract: Musculoskeletal injuries are reported as burdening the military. An identified risk factor for injury is carrying heavy loads however, soldiers are also required to wear their load as body armour. To investigate the effects of body armour on trunk and hip kinematics during military-specific manual handling tasks, 16 males completed 3 tasks while wearing each of 4 body armour conditions plus a control. Three-dimensional motion analysis captured and quantified all kinematic data. Average trunk flexion for the weightiest armour type was higher compared with control during the carry component of the ammunition box lift (p < 0.001) and sandbag lift tasks (p < 0.001). Trunk rotation ROM was lower for all armour types compared with control during the ammunition box place component (p < 0.001). The altered kinematics with body armour occurred independent of armour design. In order to optimise armour design, manufacturers need to work with end-users to explore how armour configurations interact with range of personal and situational factors in operationally relevant environments. Practitioner Summary: Musculoskeletal injuries are reported as burdening the military and may relate to body armour wear. Body armour increased trunk flexion and reduced trunk rotation during military-specific lifting and carrying tasks. The altered kinematics may contribute to injury risk, but more research is required.
Publisher: Public Library of Science (PLoS)
Date: 05-11-2018
Publisher: Informa UK Limited
Date: 24-10-2018
DOI: 10.1080/00140139.2017.1381278
Abstract: Soldiers carry heavy loads that may cause general discomfort, shoulder pain and injury. This study assessed if new body armour designs that incorporated a hip belt reduced shoulder pressures and improved comfort. Twenty-one Australian soldiers completed treadmill walking trials wearing six different body armours with two different loads (15 and 30 kg). Contact pressures applied to the shoulders were measured using pressure pads, and qualitative assessment of comfort and usability were acquired from questionnaires administered after walking trials. Walking with hip belt compared to no hip belt armour resulted in decreased mean and maximum shoulder pressures (p < 0.005), and 30% fewer participants experiencing shoulder discomfort (p < 0.005) in best designs, although hip discomfort did increase. Laterally concentrated shoulder pressures were associated with 1.34-times greater likelihood of discomfort (p = 0.026). Results indicate body armour and backpack designs should integrate a hip belt and distribute load closer to shoulder midline to reduce load carriage discomfort and, potentially, injury risk. Practitioner Summary: Soldiers carry heavy loads that increase their risk of discomfort and injury. New body armour designs are thought to ease this burden by transferring the load to the hips. This study demonstrated that designs incorporating a hip belt reduced shoulder pressure and shoulder discomfort compared to the current armour design.
Publisher: Informa UK Limited
Date: 28-07-2018
DOI: 10.1080/00140139.2017.1349933
Abstract: Search and rescue operations are necessary in locating, assisting and recovering in iduals lost or in distress. In Australia, land-based search and rescue roles require a range of physically demanding tasks undertaken in dynamic and challenging environments. The aim of the current research was to identify and characterise the physically demanding tasks inherent to search and rescue operation personnel within Australia. These aims were met through a subjective job task analysis approach. In total, 11 criterion tasks were identified by personnel. These tasks were the most physically demanding, frequently occurring and operationally important tasks to these specialist roles. Muscular strength was the dominant fitness component for 7 of the 11 tasks. In addition to the discrete criterion tasks, an operational scenario was established. With the tasks and operational scenario identified, objective task analysis procedures can be undertaken so that practitioners can implement evidence-based strategies, such as physical selection procedures and task-based physical training programs, commensurate with the physical demands of search and rescue job roles. Practitioner Summary: The identification of physically demanding tasks amongst specialist emergency service roles predicates health and safety strategies which can be incorporated into organisations. Knowledge of physical task parameters allows employers to mitigate injury risk through the implementation of strategies modelled on the precise physical demands of the role.
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.GAITPOST.2018.11.009
Abstract: Background Valgus knee braces have been reported to reduce the external knee adduction moment during walking. However, mechanistic investigations into the effects of valgus bracing on medial compartment contact forces using electromyogram-driven neuromusculoskeletal models are limited. Research question What are the immediate effects of valgus bracing on medial tibiofemoral contact forces and muscular loading of the tibiofemoral joint? Methods Sixteen (9 male) healthy adults (27.7 ± 4.4 years) performed 20 over-ground walking trials at self-selected speed both with and without an Ossür Unloader One® brace. Assessment order (i.e., with or without brace) was randomised and counterbalanced to prevent order effects. While walking, three-dimensional lower-body motion, ground reaction forces, and surface electromyograms from eight lower-limb muscles were acquired. These data were used to calibrate an electromyogram-driven neuromusculoskeletal model of muscle and tibiofemoral contact forces (N), from which muscle and external load contributions (%) to those contact forces were determined. Results Although walking with the brace resulted in no significant changes in peak tibiofemoral contact forces at the group-level, in idual responses were variable and non-uniform. At the group-level, wearing the brace resulted in a 2.35% (95% CI 0.46-4.24 p = 0.02) greater relative contribution of muscle to lateral compartment contact loading (54.2 ± 11.1%) compared to not wearing the brace (51.8 ± 12.1%) (p < 0.05). Average relative contributions of muscle and external loads to medial compartment loading were comparable between brace and no brace conditions (p ≥ 0.05). Significance Wearing a valgus knee brace did not immediately reduce peak tibiofemoral contact forces in healthy adults during normal walking. It appears this population may modulate muscle activation patterns to support brace-generated valgus moments, thereby maintaining normal walking knee moments and tibiofemoral contact forces. Future investigations are warranted to better understand effects of valgus knee brace in people with medial knee osteoarthritis using an electromyogram-driven neuromusculoskeletal model.
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.JSAMS.2018.06.013
Abstract: To determine the effects of different body armour types, carried loads, and walking speeds on trunk and lower-limb joint biomechanics. Within-subjects repeated measures to determine the effects of different body armour types, carried loads, and walking speeds on trunk and lower-limb joint biomechanics. Twenty soldiers (29.5±7.1yrs) completed a treadmill walking protocol in an unloaded (baseline) condition and wearing a control, Tiered Body Armour System (TBAS) and five different armour types (cARM1-2, pARM1) with two load configurations (15 and 30kg) for a total of eight armour×load ensembles. In each ensemble, participants walked for 10min at 1.53ms Peak plantarflexion and hip abduction moments were reduced when wearing cARM1 (p=0.040, p=0.045) and cARM2 (p=0.045, p=0.003) compared to TBAS, while carrying 30kg and/or walking fast. This suggests positive benefits of load distribution at higher task demands. Joint moments increased when participants carried greater load and/or walked faster, and the combined effects of carried load and walking speed were mostly additive. Primarily hip-borne load carriage does not negatively alter joint kinetics, and some positive adaptations occurred during tasks with higher demands. These results can inform equipment design and physical training programs for load carriage.
Publisher: Institution of Engineering and Technology (IET)
Date: 25-04-2018
No related grants have been discovered for Gavin Lenton.